Recording materials employing an electron-donating achromatic dye and an electron-accepting compound are already well known as pressure-sensitive paper, heat-sensitive recording paper, photo- and pressure-sensitive paper, heat-sensitive recording paper of the electricity application type, heat-sensitive transfer paper, etc. Such recording materials are described in detail in, e.g., British Patent 2,140,449, U.S. Pat. Nos. 4,480,052 and 4,436,920, JP-B-60-23992, JP-A-57-179836, JP-A-60-123556, and JP-A-60-123557. (The terms "JP-B" and "JP-A" as used herein mean an "examined Japanese patent publication" and an "unexamined published Japanese patent application," respectively.)
In the field of such recording materials, intensive investigations have recently been made on improvements in such properties as density of developed color and fastness of developed color.
Although attempts have been made to improve lightfastness of developed color by using an additive such as an antioxidant, singlet oxygen quencher, UV absorber, or aromatic amine derivative, this technique has problems, for example, that the additive itself has been colored and the effect produced thereby is insufficient.
Several recording materials employing an aromatic amine derivative are known. Recording materials employing a diarylamine derivative are disclosed in, e.g., JP-A-61-137770 and JP-A-61-160287, while one employing a triarylamine derivative is disclosed in JP-B-50-11294. However, these recording materials are defective in that the improvement in lightfastness of developed color is insufficient.